I have seen on other sites that some peeps hanging the bulb vertical either bare or in a cooltubes are getting some f*ing incredible results! This guy is getting 4 pounds per plant. Try to find posts by "DoubleDs" He is rocking the vertical lighting. I am not sure if I can link other forums. Check out this post.
I plan on doing my next grow vertical and I have not seen anything on specific bulbs or parts you need. I plan on just removing the shield and hanging it in the middle of a grow tent.
some bulbs are ment to be hung one way and some are universal.. its in the code..
U or VBU - vertical Base Up or VBD - Vertical Base Down
Burning Positions
VBDFilament vertical with lamp base down. VBUFilament vertical with lamp base up. HorFilament horizontal. UniversalBurns at any angle. +/-nMaximum permissible deviation of n degrees from recommended burning position.
I recently was given a bulb for free(my 400MH burnt out and i' m running my 400hps) and after doing research on the serial number MVR/STD/VBU/HO or something... I found out it was a VBU with is vertical bulb hanging down .. I have a horizontal setup with the fixture and I don't feel like altering it although I can and will when/if the HPS burns out... I also read that a Metal Vapor bulb will work in a MH fixture but not the other way around.. so I might just try it one day to see...
it's for safety reasons and life of the bulb.. they will obviously work in whatever position you put them in... BUT it's not as safe and the life of the bulb is hindered..